This invention relates to plastic injection molds, and in particular to an ejector blade assembly for ejecting plastic parts from the mold after a part has been formed.
Ejector pins are common parts of plastic injection molds. Pins of various sizes and shapes are used to help remove parts from a mold as the mold cavity is opened. Typical ejection pins are illustrated in U.S. Pat. Nos. 3,794,287; 3,852,011; 3,900,183 and 4,162,138.
While ejector pins, whether round, flat or otherwise shaped, are effective in normally ejecting plastic parts from a mold, they do suffer deficiencies. First, because pins are a unitary part, the injection molder must stock a large quantity of pins of different sizes, lengths and configurations in order to accomodate different molded parts. Secondly, because the pins are single piece structures, they are quite rigid, and any variations in a mold, whether it is due to improper tolerances or unequal expansion of one mold part relative to the other, cannot be accomodated by a pin. Such variations often lead to bending or breaking of the pins, requiring their replacement.